Presently, there are little or no developments on tools and methodologies custom-developed specifically for the characterization of Micro Electro Mechanical System (MEMS) devices for performance and quality assessment, reliability and failure analysis feasible for mass-volume manufacturing applications. One specific area is a need for a fast, cost-effective and reliable way for the in-situ, dynamic characterization of MEMS devices such as microswitches, accelerometers and gyroscopes.
The most-widely used technique for dynamic displacement measurements of MEMS devices at present is Doppler Laser Vibrometry (LDV). While accurate, this technique is essentially designed for offline application and is not suitable for inline applications owing to its intrinsically low throughput.
Further, the LDV method requires an optical beam to be precisely positioned over each structure to be characterized. This results in a severe limitation on the throughput of the LDV method. A high throughput requirement is particularly critical for die and package-level testing of dynamic MEMS products for which phonon-based characterization is ideally suited.
The LDV method also requires an encapsulated sample to be decapsulated in order for the LDV photon beam to gain direct access to the MEMS structure. This decapsulating step very often renders the MEMS device inoperable due to the loss of hermeticity and fundamental functional disruption, e.g. loss of the magnetic field in electromagnetically-latched MEMS microswitches.
Therefore, there is a need to provide an alternative MEMS characterization technique to address at least one of the above-mentioned problems.